The present invention relates to problem resolution support for free flight operations; and particularly, to a system and method for a computerized problem resolution to assist the route sector controller team in handling conflict traffic patterns by providing the capability of problem analysis and resolution of aircraft-to-aircraft, and aircraft-to-airspace problems, metering constraints and other traffic flow management parameters, including but not limited to avoidance of severe weather areas.
More particularly, the present invention relates to lateral maneuver generation for avoidance of conflict containing space blocking in accordance with right and/or left turn maneuvers to be generated in view of information contained in left and right conflict data bases using multiple iterative steps with the addition of updated conflict information to the conflict data base during each pass.
Further, the present invention relates to a system and method for problem analysis and resolution for free flight operations whereupon at a controller""s initiation, the system provides a set of candidate problem resolution advisories for a selected type of maneuver to be performed by the aircraft or for a specified aircraft problem.
Additionally, the present invention relates to calculation of a problem free block of an effectively continuous search space based on iterative principles. Maneuver parameters are calculated based on relative motion geometry to estimate the effects of planned speed changes and changes in vertical, lateral and longitudinal separation between the subject aircraft and a conflict aircraft in their mutual interdependency to each other.
In order to meet user demands and to accommodate growth in traffic, Federal Aviation Administration and National Air Space System users have embarked on an initiative known as free flight. Free flight provides users with as much flexibility in flight as possible while maintaining or increasing National Airspace System safety and predictability. The more complex traffic patterns that can result from a less structured free flight environment require enhanced problem resolution capabilities to assist the en route sector controller team in handling possible conflict situations.
As one of the free flight problem resolution supports, the User Requests Evaluation Tool (also referred to herein as URET) was developed which provides the enroute sector position controllers with automatic problem detection and trial planning capabilities, as well as a set of tools to assist in the management of flight data.
URET processes real time flight plan and track data from the National airspace system host computer, combines this data with site adaptation, key aircraft performance data, and weather conditions (such as winds and temperature) obtained from the National Weather Service in order to build four dimensional flight trajectories for pre-departure, inbound, and active instrument flight rules flights. URET also adapts its trajectories to the observed behavior of the aircraft and dynamically adjusts predicted speeds, climb rates, as well as descent rates based on the performance of each individual flight as it is tracked through enroute airspace.
URET uses the predicted trajectories to continuously detect potential aircraft problems up to 20 minutes in advance and provides a strategic alert to the appropriate sector. In addition, the predicted trajectories are the basis for the system""s trial planning capability which permits the controller to check a desired flight plan amendment for potential problems before a clearance is issued.
A two-way interface of URET permits the controller to enter the trial plan as a host flight plan amendment with the click of a button. Although, URET provides enroute sector controllers with automatic problem detection and trial planning capabilities it lacks a problem resolution function which would be helpful to the flight controllers in supporting free flight operations.
It is an object of the present invention to provide a problem resolution support for free flight operations which would generate a set of candidate problem resolution advisories being presented to the controller of the flight for decision making.
It is another object of the present invention to provide a Problem Analysis, Resolution and Ranking (also referred herein further to as PARR) method which generates resolutions for aircraft-to-aircraft and aircraft-to-airspace problems as well as the resolutions for compliance with metering time constraints of free flight operations which may be initiated either for a selected type of maneuver or for a specified aircraft with one or more problems.
When used for a selected aircraft and/or a specific problem, PARR iteratively examines a variety of resolution dimensions and directions in search of problem free trajectories to resolve the problems with the specified aircraft without introducing new problem constraints (for a given aircraft to be maneuvered). If initiated for a specific problem for example, aircraft-to-aircraft problems, the resolutions for each of the involved aircrafts is generated.
It is a further object of the present invention to provide problem analysis and resolution techniques which calculate a block of air space that an aircraft must avoid and generates a maneuver advisory for a lateral maneuver using predefined maneuver types. Calculation of maneuver parameters based on relative motion geometry to estimate the effects of planned changes each to the other is performed.
In accordance with the teachings of the present invention, a method for generating problem resolutions for free flight operations in air traffic control is provided. The method includes the steps of selecting a subject aircraft to be maneuvered; and examining continuous space enveloping the subject aircraft for a predetermined look-ahead time interval. Resolutions are then; iteratively generated in response to each problem encountered in the examined continuous space according to the closest time to occurrence, and then sequentially adding newly discovered conflicts. The method further includes the steps of; calculating parameters of requested maneuvers based on relative motion geometry, proposing a predefined maneuver of the subject aircraft; and probing each generated resolution by further examining the continuous space enveloping the subject aircraft affected by each requested maneuver.
The aforementioned functions are implemented by the Problem Analysis Resolution and Ranking (PARR) system. PARR system is well suited for generating resolutions to maneuver the subject aircraft to meet pre-assigned metering constraints, such as time of arrival, etc. PARR system operates by (a) defining a pre-conflict path constraint for the subject aircraft, which comprises straight line flight segments, (b) defining start point, end point, turn point, and off-angle of the maneuver, and (c) re-routing the aircraft through a series of fixes with respect to the flight segments in predefined off-angle parameter increments being initiated at a start point, turning the subject aircraft at a turn point, and returning the aircraft to the flight segment at an end point of the maneuver.
The dimensions of the continuous space enveloping the subject aircraft are determined by defining the required separation between a subject aircraft and a potential problem.
In PARR system, the merits of each specific maneuver are evaluated by generating a plurality of resolutions in response thereto. Thus, PARR technique is well suited for evaluation of any amendments intended to change initial flight parameters prior to approval of these amendments.
In the PARR system, a problem summary structure is formed, and data is collected which include the subject aircraft""s headings, speeds, and transitioning states at the current time. The collected data also includes; the encountered problem""s start and end times, predicted headings, speeds, transitioning states of the subject aircraft at the start and end times; minimum and maximum altitudes and true airspeeds of the subject aircraft. The system also, stores the data in the problem summary structure, and processes the data for generating the resolutions.
The lateral maneuvers include a number of types including: Direct to Maneuver end Point, Minimum Off-Angle, and Fixed Off-Angle. Vertical maneuver generated by PARR includes the above problem maneuver shapes such as Increase Altitude, Extend Climb, Early Climb, Early Extend Climb, and Step Late Descent, or the below-problem maneuver shapes, which include Decrease Altitude, Step Climb, and Step Early Descent. Longitudinal maneuvers are generally directed to speed increase or speed decrease. Each of the generated maneuvers is compatible with the operational performance envelope of the subject aircraft.
The maneuver""s parameters include turn angles and speed changes of the calculated maneuvers displayed in predefined magnitude increments. Upon completion of each maneuver, PARR returns the subject aircraft to its previous route and altitude profile.
In generating a lateral maneuver, PARR creates first and second conflict databases for respectively generating maneuvers to the left and right of the initial conflict. During each examination of the continuous space enveloping the subject aircraft, PARR adds newly discovered conflict information to a respective one of the first and second databases and then generates a resolution requesting the lateral maneuver which is intended to avoid each problem event stored in the first and second conflict databases.
PARR system determines a maneuver start point (MSP) for a Minimum Off Angle (MOA) maneuver for each discovered conflict by determining an initial MOA MSP that starts at a parameter time in the future, and for each conflict added to the conflict data base in each examination pass the MSP of a maneuver is determined by calculating a set of MSP prohibited turn intervals. The smallest MSP turn angle is selected outside of the set of MSP prohibited intervals, and an initial MSP is moved down the trajectory of the subject aircraft if the selected smallest MSP turn angle exceeds a predefined angle value,
PARR system determines a Maneuver Turn Point (MTP) and a Maneuver End Point (MEP) of an MOA maneuver by; determining an initial MEP for the MOA maneuver, and calculating a set of MTP prohibited turn intervals for each problem encountered in the conflict data base. The MTP turn angle is selected outside the set of MTP and MEP prohibited turn intervals, and the initial MEP for the MOA maneuver is moved down the trajectory of the subject aircraft if the selected MTP or resultant MEP turn angles exceed predefined limits.
Subsequent to determining the MTP and MEP of an MOA maneuver the MSP, MTP and MEP for a fixed off angle (FOA) maneuver are determined by; determining initial MSP and MEP for the FOA maneuver, calculating a set of MTP prohibited turn intervals for each problem in the conflict data base, and selecting the MTP turn angles outside the set of MTP prohibited turn intervals. The MSP is then moved downstream until outside of the set of MTP prohibited turn intervals, and the initial MEP for the FOA maneuver is moved down the trajectory of the subject aircraft if the selected MTP or resultant MEP turn angles exceed predefined limits.
Further a selection is made between an optimized MOA and FOA maneuver based on predefined criteria, for example, path length. PARR then creates the selected maneuver trajectory, probes the created trajectory of the selected maneuver for problems, and acknowledges the created maneuver trajectory as the most appropriate if the maneuver trajectory is found to be problem free. If, however, the created maneuver trajectory encounters a problem, PARR system moves the MEP calculated for the MOA and FOA maneuvers past the last problem in the conflict data base and repeats all steps for determining a Maneuver Start Point, Maneuver End Point, and Maneuver Turn Point for MOA maneuvers as well as Maneuver Turn Point and Maneuver End Point for FOA maneuvers. This process is repeated until a conflict-free maneuver is found, an iteration limit is reached, or further MSP or MEP movement is not possible (e.g., the MEP is at the destination).